Kilobyte--Megabyte--Gigabyte
Dr. Kenneth Hoffman
A kilobyte equals 1000 bytes (actually 1024 bytes but we normally round it off). A megabyte equals 1,000,000 bytes. A gigabyte equals one billion bytes. For comparison, a standard 3 1/2 inch floppy disk holds 1.44 megabytes (1,440,000 bytes). A Zip disk holds 100 or 250 megabytes. CD-ROM disks hold 650-700 megabytes. A byte is the equivalent of one ASCII character like the letters I am typing now. So you can count up the number of bytes in this message by counting the number of characters on this page including spaces. The unformatted text on this page takes 2.4 KB as an ASCII file, but the MSWord Doc file takes 26 KB. (Just take away the KB and add 000, i.e., 2,400 bytes vs. 26,000 bytes.)
Graphics and media files are memory intensive. Much more so than ASCII text. A 1024x768 medium resolution digital image (pixels times the number of lines) containing 3 bytes of color information per pixel, allowing approximately 16.8 million colors per pixel, takes 2.4 MB of storage space (1024x768x3) in uncompressed form. Images from a digital camera saved with JPG compression take between .5 MB (low resolution image) and 2.5 MB (high resolution image). High resolution images that are not compressed take approximately of 11-18 megabytes. So, we can store sixty-six 15 MB images on a 1 GB drive. Since most computer hard drives hold anywhere from 20 to 80 gigabytes that sounds like a lot of storage space. But remember, multimedia projects also contain video and music in addition to images. A DVD disk holds 4.7 Gigabytes and will store one feature film plus some additional "extras". One minute of stereo audio requires 10 MB of file space. One minute of low quality video takes about 30 MB of file space.
When preparing images for the Web small file size is extremely important. No full-screen images--320x240 pixels or smaller is best. The number of pixels per inch should not be greater than the resolution of a display monitor--72 pixels per inch. No individual image should be larger than 50 kilobytes. If there are several images on a page then make them very small, less than 10 KB per image.
So, lets look at Bytes this way:
GB = Billion $$ -- 1,000,000,000
MB = Million $$ -- 1,000,000
KB = Thousand $$ -- 1,000
Byte = 1 $
If you are new to computers, you may hear terms like kilobytes, megabytes and gigabytes. If that sounds like a foreign language to you then here is a quick run-down.
1. Units of measure
Computers work with a unit of measure called bytes.
This measure is most commonly used when describing the size of a storage media.
For example, when you visit your local computer store, the spec sheet for each computer will list RAM (computer memory) as 4, 8, 16 or 32 Gb (gigabytes) and the HDD (hard disk drive) or SSD (solid state drive) as 128, 256, 512 or 1,024 Gb.
- A kilobyte (Kb) is 1,024 bytes.
- A megabyte (Mb) is 1,024 Kb (or 1,048,576 bytes).
- A gigabyte (Gb) is 1,024 Mb.
- A terabyte (Tb) is 1,024 Gb
- A petabyte (Pb) is 1,024 Tb
Computers work in powers of 2.
For example, 2 to the power of 2 (2 squared) is 4 (2 x 2).
And 2 to the power of 3 (2 cubed) is 8 (2 x 2 x 2).
Keep multiplying by 2 and you get 16, 32, 64, 128, 256, 512, 1,024, 2,048, 4,096, 8,192 etc.
Hang around computers for long enough and you' ll start to spot these figures.
As a beginner, this doesn’t mean anything without a context. So let me give you some examples (these figures are approximate).
2. Examples of size and capacity
- A CD holds around 720Mb of data. You can fit every Beatles song on one CD!
- A DVD holds around 4.5Gb of data.
- A 4-minute song downloaded from iTunes is 4Mb (250 songs per Gb).
- A typical webpage is 3Mb (according to SpeedCurve, 2017).
- A 2 hour movie from Netflix is 500Mb (standard def) or 1Tb (high def).
- The smallest hard disk drive (HDD) or solid state drive (SSD) you can buy is 128Gb. The Windows operating system uses about 20Gb leaving over 100Gb for your stuff.
Please feel free to post any questions you have into the comments below. And before you leave this page, I want to give you one quick little action item!
ACTION ITEM: Comment below with ONE thing you picked up from this post and share how it has helped, or will help, you. It's good to share your successes because it encourages others and provides an instant boost.
Enjoy the rest of your day!
Jason loves to simplify the hard stuff, cut the fluff and share what actually works. Things that make a difference. Things that slash hours from your daily work tasks. He runs a software training business in Queensland, Australia, lives on the Gold Coast with his wife and 4 kids and often talks about himself in the third person!